I need to create an array in Javascript in my web page that contains 3 columns:

CategoryID
ReasonID
Value

So for example, I need an array to have the following info:

1,1,Value1
1,2,Value2
1,3,Value3
2,1,Value1
2,2,Value2
2,3,Value3

I will then have 2 comboboxes on my web page. The first combobox will simply contain a CategoryID value. The second combobox needs to be populated based on which CategoryID is selected in combobox 1. So for example, if CategoryID 2 is selected in combobox 1, I need combobox 2 to populated with all values from the array that contain a 2 as the first element.

An example of how to do this would be greatly appreciated.